Nokea
Which of the following is a strong acid?
- A. Acetic acid (CH₃COOH)
- B. Hydrochloric acid (HCl)
- C. Citric acid
- D. Carbonic acid (H₂CO₃)
Correct Answer: B
Rationale: Hydrochloric acid (HCl) is a strong acid because it completely ionizes in water to produce hydrogen ions, leading to a high concentration of H⺠ions in solution. This characteristic makes it a strong acid. Acetic acid (CH₃COOH), citric acid, and carbonic acid (H₂CO₃) are weak acids as they only partially ionize in water, resulting in a lower concentration of H⺠ions compared to strong acids. Therefore, hydrochloric acid is the correct choice as a strong acid.
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What is the primary function of the myelin sheath that surrounds some axons in the nervous system?
- A. To initiate nerve impulses
- B. To transmit sensory information
- C. To speed up the transmission of nerve impulses
- D. To connect neurons at synapses
Correct Answer: C
Rationale: The primary function of the myelin sheath is to speed up the transmission of nerve impulses. The myelin sheath acts as an insulating layer around the axon, allowing for faster conduction of electrical impulses along the nerve fiber. This insulation prevents the electrical signal from dissipating or 'leaking' out, which helps in the rapid and efficient transmission of nerve impulses along the axon. Choice A is incorrect because the myelin sheath does not initiate nerve impulses; it helps in conducting them. Choice B is incorrect as the myelin sheath's main role is not in transmitting sensory information but rather in facilitating the transmission of nerve impulses. Choice D is incorrect because the myelin sheath's function is not to connect neurons at synapses; instead, it is primarily involved in enhancing the speed of nerve impulse transmission.
What is the difference between a homozygous recessive genotype and a homozygous dominant genotype?
- A. Both have the same phenotype, but different genotypes.
- B. Both have the same genotype, but different phenotypes.
- C. Homozygous recessive has two dominant alleles, while homozygous dominant has two recessive alleles.
- D. Homozygous recessive has two identical recessive alleles, while homozygous dominant has two identical dominant alleles.
Correct Answer: D
Rationale: - Homozygous recessive genotype refers to an individual having two identical recessive alleles for a particular gene (e.g., rr for a trait where r represents the recessive allele).
- Homozygous dominant genotype refers to an individual having two identical dominant alleles for a particular gene (e.g., RR for a trait where R represents the dominant allele).
- The difference between the two genotypes lies in the specific alleles present in each case, with homozygous recessive having two recessive alleles and homozygous dominant having two dominant alleles.
- This genetic difference results in different phenotypes being expressed, as the dominant allele typically masks the expression of the recessive allele in heterozygous individuals.
What is the process by which decomposers break down organic matter?
- A. Photosynthesis
- B. Bioremediation
- C. Decomposition
- D. Nitrification
Correct Answer: C
Rationale: A) Photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy to produce glucose from carbon dioxide and water. This process is not related to the breakdown of organic matter by decomposers. B) Bioremediation is the use of living organisms to clean up contaminated environments. While it involves the use of microorganisms to break down pollutants, it is not specifically focused on breaking down organic matter. C) Decomposition is the process by which decomposers such as bacteria, fungi, and other organisms break down organic matter into simpler substances. This process is essential for nutrient recycling in ecosystems. D) Nitrification is the biological oxidation of ammonia or ammonium to nitrite followed by the oxidation of nitrite to nitrate by nitrifying bacteria. This process is part of the nitrogen cycle and is not directly related to the breakdown of organic matter.
How does the Pauli exclusion principle relate to the structure of the atom?
- A. It defines the maximum number of electrons allowed in each energy level.
- B. It explains why oppositely charged particles attract each other.
- C. It describes the wave-particle duality of electrons.
- D. It determines the arrangement of protons and neutrons in the nucleus.
Correct Answer: A
Rationale: The Pauli exclusion principle states that no two electrons in an atom can have the same set of quantum numbers. This principle directly influences the structure of the atom by defining the maximum number of electrons allowed in each energy level. As a result, it helps determine the electron configuration and the arrangement of electrons in different orbitals within an atom. Choices B, C, and D are incorrect as they do not directly relate to the Pauli exclusion principle's specific impact on the electron distribution within an atom.
Which property of a substance refers to the force exerted on an object due to gravity?
- A. Mass
- B. Weight
- C. Density
- D. Volume
Correct Answer: B
Rationale: The correct answer is 'Weight.' Weight is the force exerted on an object due to gravity. Mass, on the other hand, refers to the amount of matter in an object. Density is the mass per unit volume of a substance, and volume is the amount of space occupied by an object. In this context, weight specifically relates to the gravitational force acting on an object, making it the most appropriate choice among the options provided.